An inkjet recording head typically comprises outlets or nozzles that serve to eject tiny droplets of liquids used in a recording process. Situated behind the nozzles, a chamber exists that contains both electrically activated thermal electrodes producing bubbles to eject the drops, and a chamber that encloses the aforementioned electrodes.
A more conventional method of ejecting drops is commonly referred to as the roof-shooter method. In the roof-shooter method the bubble grows in the same direction as the drop is ejected. A typical manufacturing process for a roof-shooter inkjet recording head is represented in U.S. Pat. No. 5,478,606 by Ohkuma et al. Recently a back-shooter method has been disclosed in U.S. Pat. No. 5,760,804 to Heinzl et al. issued Jun. 2, 1998. In the back-shooter method the bubble grows in opposite direction to the drop ejection direction.
In the back-shooter configuration the design properties of the chamber are important in order to optimize the drop ejection and chamber refill efficiencies. These properties help achieve a high drop ejection frequency. Typical chamber structures are disclosed in U.S. Pat. No. 6,019,457 to Silverbrook issued Feb. 1, 2000 and U.S. Pat. No. 6,561,626 to Jae-sik Min et al. issued May 13, 2003. The aforementioned prior art describes a chamber, hemispheric in shape, formed by isotropic etching with an ink inlet, the same diameter as the nozzle, formed by anisotropic etching through the nozzle.
To control the refill impedance of an inkjet chamber, it is important to be able to control the ink inlet diameter. A recent publication, U.S. patent application Ser. No. 2003/0109073 Al by Park et al., discusses a method of manufacturing a monolithic ink-jet printhead. The discussion includes the preparation of a silicon substrate, the forming of an ink passage comprised of a manifold that supplies ink, an ink chamber filled with ink supplied from the manifold, an ink channel connecting the ink chamber to the manifold, and a nozzle through which ink is ejected. The ink chamber is formed by isotropically etching the silicon substrate through the nozzle to form the shape of the ink chamber in a hemisphere. The ink channel is formed by anisotropically dry etching the silicon substrate from the bottom surface of the ink chamber through the nozzle. The passage of a Xe—F2 gas through the ink passage dry etches the wall of the ink passage, and permits the smoothing of the wall that more precisely adjusts the passage to some design dimension thereby improving the printing performance of the printhead. This process, however, is limited in the scope of what it can produce. Often there are additional problems and technical needs associated with the production of print-heads that require unique inkjet chamber geometries to further enhance writing performance, that are economically unattainable by present processes.
Consequently, a need exists for overcoming the above-described shortcomings.